of 'Oral food challenges for diagnosis and management of food allergies'

BACKGROUND:
Although peanut allergy may recur, the frequency with which this occurs is unknown.

OBJECTIVE:
The goals of this study were to determine the rate of peanut allergy recurrence, identify risk factors for recurrent peanut allergy, and develop specific recommendations for the treatment of patients with resolved peanut allergy.

METHODS:
Children who outgrew peanut allergy were evaluated with questionnaires, skin tests, and peanut-specific IgE levels. Patients were invited to undergo a double-blind, placebo-controlled food challenge (DBPCFC) unless the history of a possible recurrence reaction was so convincing that a challenge would be potentially dangerous.

RESULTS:
Sixty-eight patients were evaluated. Forty-seven patients continued to tolerate peanut, of whom 34 ingested concentrated peanut products at least once per month and 13 ate peanut infrequently or in limited amounts but passed a DBPCFC. The status of 18 patients was indeterminate because they ate peanut infrequently or in limited amounts and declined to have a DBPCFC. After excluding 12 patients originally diagnosed with peanut allergy based solely on a positive skin prick test or peanut-specific IgE level, 3 of 15 patients who consumed peanut infrequently or in limited amounts had recurrences, compared with no recurrences in the 23 patients who ate peanut frequently ( P = .025). The recurrence rate was 7.9 (95% CI, 1.7% to 21.4%).

CONCLUSION:
Children who outgrow peanut allergy are at risk for recurrence, and this risk is significantly higher for patients who continue largely to avoid peanut after resolution of their allergy. On the basis of these findings, we now recommend that patients eat peanut frequently and carry epinephrine indefinitely until they have demonstrated ongoing peanut tolerance.

BACKGROUND:
Although there is concern that food allergy reactions may negatively affect the natural history of food allergy, the impact of reactions on food-specific IgE (sIgE) levels or skin prick test (SPT) wheal size is unknown.

OBJECTIVE:
To measure the effects of allergic reactions on SPT wheal size and sIgE concentrations to milk, egg, and peanut.

METHODS:
Participants included 512 infants with likely milk or egg allergy enrolled in a multicenter observational study. Changes in sIgE level and SPT wheal size to milk, egg, and peanut were measured before and after oral food challenge (OFC) or accidental exposure for 377 participants.

RESULTS:
The median age of the cohort at the time of analysis was 8.5 years (67% males). There were no statistically significant changes in sIgE level or SPT wheal size after positive OFC to milk, egg, or peanut (n = 20-27 for each food). Change in sIgE level and SPT wheal size was measured after 446 and 453 accidental exposure reactions, respectively. The median change in sIgE level was a decrease of 0.33 kUA/L (P<.01) after milk and 0.34 kUA/L (P<.01) after egg reactions, but no other statistically significant changes in sIgE level or SPT wheal size were observed for milk, egg, or peanut. When we limited the analysis to only those participants who had diagnostic testing done within 6 months of an accidental exposure reaction, we found that peanut SPT wheal size increased by 1.75 mm (P<.01), but a significant increase was not noted when all participants with testing done within 12 months were considered.

CONCLUSIONS:
The results suggest that reactions from OFCs and accidental exposure are not associated with increases in sensitization among children allergic to milk, egg, or peanut.

AD

Department of Pediatrics, Icahn School of Medicine at Mount Sinai, New York, NY. Electronic address: scott.sicherer@mssm.edu.

Cutoffs (decision points) of the peanut skin prick test (SPT) and specific IgE level for predicting peanut allergy have been proposed. It is not known whether decision points indicating a significant risk of severe reactions on challenge differ from those indicating probable allergy. We aimed at determining the usefulness of allergy tests for predicting the risk of anaphylaxis on challenge following the ingestion of up to 12 g of peanut in peanut-sensitized children. Children attending the Allergy Clinic who had a positive peanut SPT and completed open-label in-hospital peanut challenges were included. The challenge protocol provided for challenges to be continued beyond initial mild reactions. Eighty-nine in-hospital peanut challenges were performed. Thirty-four were excluded as the challenge was not completed, leaving 55 for analysis. Children who completed the challenge and did not react (n = 28) or reacted without anaphylaxis (n = 6) represented the comparison group (n = 34). The study group comprised 21 children whose challenge resulted in anaphylaxis. The mean peanut SPT wheal size and specific IgE level were associated with the severity of reactions on challenge. Among the 21 children, who developed anaphylaxis, in only 3 cases was anaphylaxis theinitial reaction. Unexpectedly, a history of anaphylaxis was not predictive of anaphylaxis on challenge. Anaphylaxis developed at cumulative doses of peanut ranging from 0.02 to 11.7 g. Provided that a fixed amount of peanut is ingested, available tests for peanut allergy may assist in predicting the risk of anaphylaxis during challenge in peanut-sensitized children.

BACKGROUND:
Peanut allergy affects 1% of children, and for those with persistent disease, few data have been published on trends in peanut-specific immunoglobulin E (P-IgE) levels or the value of P-IgE in predicting reaction severity.

OBJECTIVE:
The primary outcome was the frequency of inadvertent peanut exposure. Secondary outcomes included clinical characteristics, trends in P-IgE, characteristics of accidental exposures, and predictors of reaction severity in patients with persistent peanut allergy.

METHODS:
Records of patients with persistent peanut allergy were reviewed. Other allergic conditions, P-IgE levels, and peanut exposures were documented.

RESULTS:
Seven hundred eighty-two patients were studied, 524 of them male. The median age at initial observation was 1.4 years; the median duration of follow-up was 5.3 years. Of the 782 patients, 93.1% were avoiding other foods, 70.8% had atopicdermatitis, 57.3% allergic rhinitis, and 55.8% asthma. The median initial P-IgE was 28.0 kU/L, and the median peak P-IgE was 68.1. Six hundred eighty-five exposures were seen among 455 patients: 75.9% ingestion, 13.6% contact, 4.5% airborne. 73.7% resulted in urticaria/angioedema, 22.2% lower respiratory symptoms, 21.2% gastrointestinal symptoms, and 7.7% oral erythema/pruritus. Treatment included antihistamines (33.4%), emergency department visits (16.5%), epinephrine (13.1%), corticosteroids (7.7%), albuterol (3.2%), no treatment (26.3%), and not recorded (29.6%). The rate of postdiagnosis ingestion was 4.7%/year; exposures with severe reactions, 1.6%/year; reactions treated with epinephrine, 1.1%/year. Reaction severity did not change with repeated exposure. Severe reactions were associated with higher P-IgE, but not with age, sex, or asthma.

CONCLUSION:
In this referral population, the rates of accidental peanut exposures and severe reactions were low. There was a strong association between higher P-IgE levels and reaction severity.

AD

Department of Medicine, Division of Allergy and Clinical Immunology, The Johns Hopkins University School of Medicine, 600 North Wolfe St, Baltimore, MD 21287, USA.